I think more people use it than some seem to think.Pure anecdotal observation here but, almost every time I hear mention of the Halo 5 campaign it's in the context of playing it solo with the AI companions. I was honestly expecting to hear more about people rolling 4-deep through the campaign but I haven't. Could the splitscreen-only playerbase have represented a larger portion compared to online coop players than they had thought?
Split Screen is great even though i don't use it myself that often.